Altho that’s true, the number of black slaves in Texas at that time was small (Maybe 5000?). Really what caused the break was the * Siete Leyes* (Seven Laws) of 1835, which also caused several other Mexican states to proclaim independence. The Mexican government had also offered immigrants a exemption from Property taxes for 10 years, but rescinded it. Also of course people of American descent outnumbered those of Mexican descent in the area by more than 4-1.
So, no doubt slavery was part of it, but it’s not like that was THE core basis, as in the Civil War.